Semiconductor manufacturing typically entails performing a number of processes, including thin film deposition, photolithography, oxidation, nitration and so forth. A convention apparatus for performing such processes is known as a “processing tool” and may include several processing chambers coupled to a central transfer chamber. One or more load lock chambers may also be coupled to the transfer chamber. The load lock chamber or chambers are used to load substrates into and remove substrates from the processing tool.
Due to the complexity of many semiconductor manufacturing processes, the number of individual process steps to be performed frequently exceeds the number of process chambers included in a processing tool. Accordingly, it is generally necessary to transport substrates from one processing tool to another. It is customary, during such transportation of substrates, to carry the substrates in a closed container known as a “pod.” Conventional pods include a door which seals the pod so that the substrates are isolated from the ambient atmosphere while in the pod. In this way, the possibility of contamination of the substrates can be reduced.
It is conventional to provide a pod loading station in front of a processing tool for the purpose of receiving a pod containing substrates, opening the pod door, and allowing substrates to be removed from the pod and transferred to the processing tool. When processing of the substrates is complete, the substrates are placed back in the pod, the pod door is closed and locked, and the pod is taken away from the pod loading station for delivery to another processing tool, or to a storage location, etc.
It may sometimes occur that the replacement and locking of the pod door, after processing and replacement of the wafers in the pod, may be performed improperly. If this occurs, the pod door may become displaced or may fall off the pod, which can result in contamination or serious damage to the substrates contained in the pod.